NIR/red light for lateral neuroprotection

ABSTRACT

The use of red or near infrared light upon neurons of the lumbar plexus that are in distress due to retraction-induced ischemia. The surgeon may protect nerves made ischemic in the surgery by:
     a) making an incision in a patient,   b) inserting an access device into the patient through the incision to at least partially create a path to a spine of the patient, and   c) irradiating nervous tissue adjacent the path with an amount of NIR or red light effective to provide neuroprotection.

CONTINUITY DATA

This application is a continuation of U.S. Ser. No. 13/784059, entitledNIR-Red Light for Lateral Neuroprotection, filed Mar. 4, 2013 whichclaims priority from U.S. provisional patent applications U.S. Ser. No.61/705,712, entitled “NIR/Red Light for Lateral Neuroprotection”, filedSep. 26, 2012, and U.S. Ser. No. 61/748,489, entitled “NIR/Red Light forLateral Neuroprotection”, filed Jan. 3, 2013, the specifications ofwhich are incorporated by reference in their entirety.

BACKGROUND OF THE INVENTION

The lateral access approach is frequently utilized to deliver interbodyfusion cages to the lumbar spine. In comparison to conventional anterioror posterior approaches to the lumbar spine, the lateral approach isthought to minimize posterior and/or anterior tissue damage as well asreduce surgery time, associated blood loss, vascular damage andinfection risk.

When the lateral access approach is utilized, the surgeon may usesequential dilation followed by tissue retraction in order to provide aminimally invasive path to the disc space. In addition, neuromonitoringis typically undertaken in order to avoid disturbing nerves residing inthe lumbar plexus. In particular, one of the cannulae used in thesequential dilation or the retractor used for retraction may be fittedwith an electrode capable of detecting a proximate nerve.

Despite these efforts, there still appears to be a significant incidenceof neural deficit associated with the lateral approach to the spine. Forexample, there appears to be about a 30-35% incidence of transient butsevere leg pain in patients undergoing an L4-L5 intervertebral fusion bya lateral approach.

Because of the proximity of the neural elements, in particular thefemoral nerve, to the center of the disc space, the transpsoas lateralsurgical approach to the L4-L5 disc space will likely causeintraoperative displacement of neural structures from their anatomiccourse during retractor dilation. Careful attention should be paid toretractor placement and dilation time during transpsoas lateral accesssurgery, particularly at the L4-L5 disc. Davis, J Bone Joint Surg Am.2011 Aug. 17; 93(16):1482-7.

U.S. Pat. No. 7,686,839 (Parker) discloses a phototherapy treatmentdevices include a light emitter that is adapted to be placed in closeproximity to a wound for applying light/heat energy to the wound to aidin the healing process. The light emitter may comprise a light guidethat receives light from a light source or a light source that isaffixed to a substrate used to position the light source over the wound.

SUMMARY OF THE INVENTION

The present invention is directed to using the neuroprotective abilitiesof near-infrared (NIR) or red light to decrease the incidence orseverity of neural deficits in patients undergoing a lateral fusion.

The literature provides in vitro and in vivo instances of NIR lightproviding neuroprotection to ischemic cells. Zhang teaches that NIRlight protects cardiomyocytes from hypoxia and reoxygenation and does soby a nitric oxide-dependent mechanism. Zhang, J. Molec. Cell.Cardiology, 46, 2009, 4-14. Lapchak, Neuroscience, 148(2007) 907-914reports that transcranial near infrared light therapy improves motorfunction following embolic strokes in rabbits.

It is believed that when a retractor is expanded during the lateralapproach, increased pressure is placed upon the tissue adjacent theretractor tip, including nerves of the lumbar plexus and theirassociated arteries. The increased pressure upon these arteries causesan ischemic situation in the associated nerves, leading to the neuraldeficit.

Without wishing to be tied to a theory, it is believed that NIR/redlight will help these distressed neurons cope with the ischemia byenhancing the energetics of their mitochondria.

Therefore, in accordance with the present invention, there is provided amethod of protecting nerves, comprising the steps of:

-   -   a) making an incision in the patient,    -   b) inserting an access device into the patient through the        incision to at least partially create a path to a spine of the        patient,    -   c) irradiating nervous tissue adjacent the path with an amount        of NIR or red light effective to provide neuroprotection.

Also in accordance with the present invention, there is provided (anassembly comprising:

-   -   a) a retractor comprising a first blade having a distal end        portion having a light delivery catheter thereon, and    -   b) NIR/red light source connected to the light delivery        catheter.

DESCRIPTION OF THE FIGURES

FIG. 1a discloses a portion of a wall of a cannula or retractor of thepresent invention having a light emitting window W and an electrode E.

FIG. 1b discloses a light catheter shaped to fit within the channel ofthe wall of FIG. 1 a.

FIG. 2a discloses a top view of a retractor of the present invention inits closed configuration.

FIG. 2b discloses a top view of a retractor of the present invention inits open configuration.

FIG. 2c discloses a perspective view of a retractor of the presentinvention in its closed configuration.

FIG. 3a discloses a conventional tracheal dilator.

FIG. 3b discloses an arm of a tracheal dilator modified to provide bothan electrode and a window.

FIG. 4 discloses an embodiment of a retractor having a red lightemitter.

FIG. 5 discloses an embodiment of a retractor wherein the distal-most20% of the retractor blade emits NIR/red light.

FIG. 6 discloses an embodiment of a retractor in which the retractorblade emits NIR/red light, at least one blade is made of a substantiallyoptically clear material and NIR/red light is “injected” into the bladefrom the proximal end portion of the blade.

FIG. 7 discloses an embodiment of a retractor in which reflectiveparticles are present throughout the length of the blade.

FIG. 8 discloses an embodiment of a retractor in which the proximalportion of the optically clear blade is substantially free of reflectiveparticles while the distal portion of the optically clear bladecomprises light reflective particles,

FIG. 9 discloses an embodiment of a retractor in which the proximalendportion of the blade is fitted with at least one receptacle that isadapted to receive a distal end of a fiber optic cable.

FIG. 10 discloses an embodiment of a retractor in which a connector isadapted to receive a fiber optic cable and is located on the outersurface of the proximal end portion of the blade,

FIG. 11 discloses an embodiment of a retractor in which a retractorblade has a light guide attached to the distal portion of the outersurface of the blade.

FIG. 12 discloses an embodiment of a retractor in which a light guide(that is attached to the distal end portion of the outer surface of theblade) comprises a plurality of optical fibers having roughened outersurfaces.

FIG. 13 discloses an embodiment of a retractor in which a light guide(that is attached to the distal end portion of the outer surface of theblade) comprises a single optical fiber having a plurality of lightreflective particles contained therein, and wherein the single opticalfiber is wound in a coil shape

FIG. 14 discloses an embodiment of a retractor in which an outsidesurface of the blade has an array of NIR/red LEDs attached thereto.

FIG. 15 discloses an embodiment of a retractor in which a lightdiffusing panel is attached to the outside surface of the blade andlight is delivered to a backside of the panel.

FIG. 16 discloses an embodiment of a retractor in which a blade may be abiocompatible metal and have a bore beginning at the proximal endsurface, running distally through the blade and terminating as anopening upon the distal end portion 169 of the outer surface of theblade.

FIG. 17 discloses an embodiment of a retractor in which at least oneblade of the retractor is made of an optically clear material and lightis shined laterally through the distal portion of this blade from ahand-held light source temporarily lowered into the distal portion ofthe working channel of the retractor.

DETAILED DESCRIPTION OF THE INVENTION

For the purposes of the present invention, an arm of a retractor isconsidered to be a type of blade.

For the purposes of the present invention, a “NIR/red light emitter” maycomprise a distal end of a light delivery catheter connected to aNIR/red light source. For the purposes of the present invention, a“NIR/red light emitter” may also comprise an NIR/red light LED.

In one method of the present invention, the patient is placed in adirect lateral decubitus position, and electrodes are applied to thepatient's skin. The table should be appropriately flexed so that thepatient's pelvis tilts away from the spine, thereby maximizing access toL4-5.

Next the operative disc space is identified using lateral fluoroscopyand two K-wires are crossed on the skin to mark the center of the disc.

An incision is made in the side of the spinal patient to afford theopportunity for a lateral retroperitoneal approach.

Next, blunt dissection of the oblique abdominal muscles is performed.This is followed by bluntly penetrating the transversalis fascia toexpose the retroperitoneal fat and visualize the psoas muscle.

Next, a first of a series of cannulated dilators is introduced into thepsoas muscle. Its distal end should approach the target disc justanterior to the medial-lateral midline of the disc. Sequential dilationis then performed by passing the next largest dilator over the firstdilator, and so on. Next, a guidewire is passed through the firstcannula until its distal end reaches about half way into the disc.

Next, a retractor is slid over the largest cannula until it reaches thedesired depth. The retractor is then secured to a rigid arm to hold theretractor in place for the remainder of the surgery. The dilators arethen removed.

The retractor is then expanded to its desired diameter.

Next, the desired portion of the annulus fibrosus is removed, and thedesired portion of the nucleus pulposus is removed. The endplates arethen prepared. The disc space is then distracted by a spreader, and thentrialed to select the appropriately sized fusion cage.

An intervertebral lateral fusion cage adapted for a lateral approach maythen be filled with a bone growth substance, passed through the pathmade by the access device, inserted into the disc space, and finallylightly impacted into place.

At least one of the cannulae and/or retractor is fitted with anelectrode so that neuromonitoring can take place during the approach tothe disc by those instruments. When the neuromonitoring system indicatesthat the so-fitted cannula and/or retractor has come too close to anerve of the lumbar plexus, the system provides a warning signal, suchas an audible sound or a visual cue (such as a red stop sign displayedon a computer screen). The surgeon then adjusts the approach of theinstrument away from the affected nerve and provides appropriate redlight therapy to that nerve.

In one embodiment, a blade tip of a retractor of the present inventionis fitted with both an electrode and a red light emitter, and that thesecomponents are substantially adjacent one another on the blade tip. Whenthe neuromonitoring system indicates that this blade tip has come tooclose to a nerve during its expansion, the system provides a warningsignal, and the surgeon then activates the red light emitter for adesired period such as 90 seconds. After the therapy is finished, thesurgeon can then move the blade away from the nerve.

The following section describes the downstream metabolic events thatoccur in LLT after therapy has been provided.

It is believed that the hypometabolism of the ischemic cell can bereversed or attenuated by low level laser therapy (“LLLT”) treatment ofthese cells with red/near infrared light (“red/NIR light”). Inparticular, it is believed that red/NIR light will beneficially act uponthe ischemic cells through the following avenues:

-   a) increasing the amount of ATP in the ischemic cells;-   b) increasing the amount of BDNF in the ischemic cells;-   c) increasing the amount of bcl-2 in the ischemic cells,

Oron, Photomed Laser Surg. 2007 June; 25(3):180-2. (2007) reports thatin vitro red/NIR light approximately doubles the amount of ATP inneurons. Since metabolic processes of the neuron substantially use ATPas their fuel, it is believed that the increase in ATP afforded by LLLTwill help normalize the hypometabolism in the ischemic cells experiencedby the patient.

As discussed above, it is now believed that the survival of an ischemicneuron may lie in their ability to induce pro-survival proteins (i.e.,neurotrophins) such as brain-derived neurotrophic factor (BDNF). It hasbeen shown that LLLT acts upon neurons to increase BDNF 5× in neurons(Byrnes Lasers Surg Med. 2005 August; 37(2):161-71.), and (Anders, IEEEJ. Quantum Electronics, 14/1 Jan./Feb. 2008, 118-125).

bcl-2 is an anti-apoptotic gene that has been implicated in mediatingneuronal plasticity. Manji, Psychopharmacol Bull. 2001 Spring;35(2):5-49. In this respect, red light has been shown to increase bcl-2in neurons (Liang, Neuroscience. 2006 May 12; 139(2):639-49,) and(Zhang, supra, 2008).

Further without wishing to be tied to a theory, it is further believedthat red/NIR light therapy of the ischemic cells will provide a numberof additional advantages to the spinal patient.

First, red/NIR light therapy is a completely non-toxic therapy. Thus, itappears that its use poses no known danger to the patient. Therefore,red/NIR light therapy/LLLT can be used by the surgeon without anyapparent risk to the patient.

Second, it is believed that red/NIR light therapy will work much morequickly than conventional therapeutics, with LLLT providing a firstround of benefit within about an hour of the initial irradiation and asecond round of benefit within a few days of the initial irradiation.

Respecting highly acute events, Oron (supra, 2007) reports that in vitrored/NIR light increases ATP in neurons within 10 minutes of theapplication of red/NIR exposure, while Zhang reports that LLLT activatesPKC in neurons within one hour of the irradiation (Zhang, supra, 2008).Thus, two mechanisms are acting favorably upon the patient within anhour of LLLT treatment.

Respecting more subchronic events, Anders, 2008 reports that red/NIRlight increases BDNF in neurons within 3-7 days of the beginning ofred/NIR light exposure. Zhang (2008)/Liang & Whelan (2006) report thatred/NIR light increases bcl-2 in neurons within 6-28 hours respectivelyof the beginning of red/NIR light exposure.

Preferably, the red/NIR light of the present invention has a wavelengthof between about 600 nm and about 1500 nm, more preferably between about600 nm and about 1000 nm. In some embodiments, the wavelength of lightis between 800 and 900 nm, more preferably between 825 nm and 835 nm. Inthis range, NIR/red light has not only a large penetration depth(thereby facilitating its transfer to the fiber optic and OFC), butWong-Riley reports that cytochrome oxidase activity is significantlyincreased at 830 nm, and Mochizuki-Oda reported increased ATP productionvia a 830 nm laser.

In some embodiments, the wavelength of light is between 600 and 700 nm.In this range, Wong-Riley reports that cytochrome oxidase activity wassignificantly increased at 670 nm. Wollman reports neuroregenerativeeffects with a 632 nm He—Ne laser.

In some embodiments, the light source is situated to irradiate adjacenttissue with between about 0.01 J/cm² and 20 J/cm² energy. Withoutwishing to be tied to a theory, it is believed that light transmissionin this energy range will be sufficient to increase the activity of thecytochrome c oxidase around and in the target tissue. In someembodiments, the light source is situated to irradiate adjacent tissuewith between about 0.05 J/cm² and 20 J/cm² energy, more preferablybetween about 2 J/cm² and 10 J/cm² energy.

The present inventor are aware of at least two reports of very favorableeffects of red/NIR light irradiation of neuronal cells at fluences ofless than 1 J/cm². As discussed above, Byrnes, Lasers Surg Med. 2005August; 37(2):161-71 found that a significant (P<0.05) increase in brainderived neurotrophic factor (BDNF) and glial derived neurotrophic factor(GDNF) in the 0.2 J/cm² group in comparison to the non-irradiated group.Oron, Photomed Laser Surg. 2007 June; 25(3):180-2 reports that normalhuman neural progenitor (NHNP) cells were grown in tissue culture andwere treated by Ga—As laser (808 nm, 50 mW/cm², 0.05 J/cm²). They foundthat the quantity of ATP in laser-treated cells 10 minutes after laserapplication was 7513+/−970 units, which was significantly higher(p<0.05) than the non-treated cells, which comprised 3808+/−539 ATPunits. In sum, Oron found that the neuronal ATP level was essentiallydoubled by LLLT. In addition, Byrnes, Lasers Surgery Medicine, March.2005, 36(3) 171-85 reports that dosages as low as 0.001 stimulatecellular activity (such as DNA, RNA and protein production,proliferation and motility). Therefore, it is believed that fluences aslow as about 0.01 J/cm² (and possibly even about 0.001 J/cm²) will beeffective in providing therapy to the pertinent ischemic cells neuronsof the patient.

In some embodiments, the light source is situated to produce about 10-90milliwatt/cm², and preferably 7-25 milliwatt/cm².

In accordance with US Patent Publication 2004-0215293 (Eells), LLLTsuitable for the neuronal therapy of the present invention preferablyhas a wavelength between 630-1000 nm and power intensity between 25-50mW/cm² for a time of 1-3 minutes (equivalent to an energy density of2-10 J/cm²). Eells teaches that prior studies have suggested thatbiostimulation occurs at energy densities between 0.5 and 20 J/cm².Wong-Riley. J. Biol. Chem. 2005 Feb. 11, 280(6), 4761-71 reports thatfluences as high as 30 J/cm² appear to be effective in preventing celldeath in neurons exposed to the mitochondrial poison KCN. In someembodiments, the preferable energy density of the present invention isbetween 0.1 and about 30 J/cm², more preferably between 0.5-20 J/cm²,most preferably between 2-10 J/cm². In summary, a preferred form of thepresent invention uses red and near infrared (red/NIR) wavelengths of630-1000, most preferably, 670-900 nm (bandwidth of 25-35 nm) with anenergy density fluence of 0.5-20 J/cm², most preferably 2-10 J/cm², toproduce photobiomodulation. This is accomplished by applying a targetdose of 10-90 mW/cm², preferably 25-50 mW/cm² LED-generated light forthe time required to produce that energy density.

It is further believed that red/NIR light irradiation of neurons willproduce a significant upregulation in brain derived neurotrophic factor(BDNF) and glial derived neurotrophic factor (GDNF). Byrnes, Lasers SurgMed. 2005 August; 37(2):161-71 reports that olfactory ensheathing OECswere purified from adult rat olfactory bulbs and exposed to 810 nm light(150 mW; 0, 0.2, or 68 J/cm²). Byrnes found that a significant (P<0.05)increase in BDNF, GDNF and collagen expression in the 0.2 J/cm² group incomparison to the non-irradiated and high dose groups.

Of note, it has been reported that the neuroprotective effects ofred/NIR light can be effected by a single irradiation on the order ofminutes. Wong-Riley, J. Biol. Chem. 2004, e-pub November 22, reportsthat irradiating neurons with 670 nm red light for only ten minutesresults in neuroprotection. Similarly, Wong-Riley Neuroreport 12(14)2001: 3033-3037 reports that a mere 80 second dose of red lightirradiation of neuron provided sustained levels of cytochrome oxidaseactivity in those neurons over a 24 hour period. Wong-Riley hypothesizesthat this phenomenon occurs because “a cascade of events must have beeninitiated by the high initial absorption of light by the enzyme”. Theefficacy of a single irradiation would appear to be important for theapplication of LLLT to in-surgery neuroprotection.

In some embodiments, the red light irradiation is delivered in acontinuous manner. In others, the red light irradiation is pulsed inorder to reduce the heat associated with the irradiation.

In some embodiments, red light is combined with polychrome visible orwhite light.

In some embodiments, the light source is adapted so that at least 50% ofits emission is NIR or red light (or a combination of each), preferablyat least 75%, more preferably at least 90%.

In some embodiments, the NIR/red light is applied to the nerves forbetween about 30 and 300 seconds.

In some embodiments of the present invention, the light used toirradiate the nerves of the lumbar plexus is near-infrared (NIR) light.In others, it is red light. Each of NIR and red light are adequatelyabsorbed by cytochrome c oxidase so as to increase its activity andeffect neuroprotection. While NIR light has the advantage of penetratingsubstantially deeper into the tissue, red light has the advantage ofbeing visually detectable by the surgeon. For the reason, red light maybe more desirable when then the target nerves are close to the red lightemitter mounted on the access instrument.

In some embodiments, the NIR/red light therapy is carried out after awarning. This warning may come from a neuromonitoring system. It mayalso come from the surgeon or attendant seeing a twitch in an affectedmuscle.

In some embodiments, the irradiation is carried out automatically viadirection from a neuromonitoring system after the warning. In others,the irradiation is carried out via actuation (typically, manually) ofthe red light emitter by the surgeon.

In some embodiments, the irradiation may be carried out prophylacticallyupon the nerves of the lumbar plexus. In some embodiments, thisprophylactic treatment is carried out upon insertion of the first accessinstrument into the psoas muscle.

In some embodiments, the irradiation may be carried out after theretractor has been expanded, whether or not a warning has been given.

It is understood by the present inventors that providing NIR/red lightin the amounts described herein has no detrimental effect to the healthycells, and so may be provided prophylactically without cause forconcern.

In some embodiments, the neuromonitoring system provides a warning whenit detects a nerve within a predetermined proximity. In someembodiments, the neuromonitoring system provides a warning when itdetects a decline in nerve status or health.

In preferred embodiments, the access path of the present invention leadsto an intervertebral disc space. In embodiments thereof, the path is oneof a lateral path to an intervertebral disc space; a posterolateral pathto an intervertebral disc space; an anterolateral path to anintervertebral disc space; or a translaminar path to the intervertebraldisc space.

In some embodiments, the access device of the present invention is acannula. Preferably, the cannula is one of a series of sequentiallylarger cannulae designed to dilate a tissue region. Preferably, thecannulated access device has an electrode fitted on its distal endportion. Preferably, the cannulated access device also has a red lightemitter fitted on its distal end portion.

In other embodiments, the access device of the present invention is aretractor. Preferably it is an expandable retractor having at least twoand preferably at least three blades. Preferably, at least one blade ofthe retractor has an electrode fitted on its distal end portion.Preferably, the blade also has a red light emitter fitted on its distalend portion.

In some embodiments, the access device has a NIR/red light emittermounted thereon, and irradiation of the affected nerve is carried out byactuation of the mounted red light emitter. In preferred embodimentsthereof, the red light emitter comprises a NIR/red light source mountedupon the access device. More preferably, the NIR/red light source is adiode. In other embodiments thereof, the red light emitter comprises alight delivery catheter that is connected to a NIR/red light sourcelocated outside the patient's body.

FIG. 1a discloses a portion of an arc-shaped wall 1 of a cannula orretractor of the present invention, wherein the wall has an outersurface 3 having a light emitting window W and an electrode E thereon.

In some embodiments, the cannula or retractor has a wall having an innersurface 5 and an outer surface 3. The wall may have an L-shapedlongitudinal channel 7 provided therein running from the proximal endportion to the distal end portion of the wall and terminating at theouter surface of the distal end portion of the wall. FIG. 1b disclosesthat the light delivery catheter 9 can be L-shaped and designed to fitsecurely in the channel, so that it runs down the length of the wall andalso terminates at the outer surface of the distal end portion of thewall in the form of a window W. The proximal end of the catheter canhave a luer lock connection (not shown) designed to fit a mating luerlock connection of a NIR/red light source. The surfaces of the lightdelivery catheter can (with the exception of the luer lock surface andthe window) be coated with a light reflecting material such as ametallic coating, so that light will enter at the luer lock connectionand exit through the window.

In some embodiments, the light delivery catheter is secured to thechannel of the wall via a taper-lock configuration, thereby allowing itssecure fitting and its removal.

In some embodiments, a metallic strip may be coated across a portion ofthe surface of the window to function as an electrode.

Now referring to FIGS. 2a-2c , in some embodiments of the presentinvention, the retractor 11 comprises a first blade 13 having a distalend portion 15 having an NIR/red light emitter window W thereon. In someembodiments, the distal end portion of the first blade has an outersurface 17 and an inner surface, and the NIR/red light emitter window Wis mounted on the outer surface. In this situation, the emitter window Wis close to the nerves identified by the electrode.

In most embodiments related to a lateral spinal approach, the retractorfurther comprises a second blade 19. Typically, the first and secondblade are movable with respect to one another so as to create a firstclosed condition and a second expanded condition. This expandedcondition usually provides a path for delivering an implanttherethrough. In preferred embodiments, the retractor further comprisesa third blade (not shown).

In preferred embodiments, the NIR/red light emitter mounted on theretractor is electrically connected to a neuromonitoring system, so thata signal from the neuromonitoring system can automatically actuate thered light emitter. However, in others, the emitter can be a stand-alonedevice independently actuatable by the surgeon. In preferredembodiments, the NIR/red light emitter is a NIR/red light source mountedon the outer surface of the first blade, while in others the NIR/redlight emitter comprises a light delivery catheter connected to a NIR/redlight source located outside the patient's body. In such situations, thefirst blade further preferably comprises a proximal portion 21, and thelight delivery catheter runs along the proximal portion of the blade andterminates in the distal end portion of the blade.

In one embodiment, a blade of a retractor of the present invention isfitted with both an electrode and two red light emitters, and theseemitters are disposed on either side of the electrode.

In some embodiments, the retractor comprises at least three basecomponents, each of which having a blade extending substantiallyperpendicularly therefrom. Preferably, the outer surface of the distalend portion of at least one blade has both a red/NIR light emitterwindow W and an electrode E thereon (as in FIG. 2c ). The electrode canbe formed from simply making the blade out of a conductive metal andcoating the entire component (excepting the proximal end surface and thedistal end surface that is electrode E) with a nonconductive polymer.The red/NIR light emitter window W can be formed as described above.

In some retractor embodiments (as in FIG. 2b ), each base 25 has aprojection 27 extending from a first side surface 29 and a recess (notshown) extending into a second side surface 31, so that the three basescan adjustably mate with one another via actuation of keys. Each basealso has a curved side surface 33 forming substantially a 120 degree arcso that the three curved side surfaces form a circular opening 35 whenmated (as in FIG. 2a ).

In some retractor embodiments, each blade has a proximal end portionconnected to its respective base and a distal end portion having both ared/NIR light emitter window W and an electrode E thereon.

In some embodiments, the first blade has an axial cross-sectionsubstantially defining an arc. This describes most conventionalretractor blades, and allows a plurality of such blades to be axiallyslid over a cannula.

In some embodiments, the first blade has a proximal end portion and adistal end portion, and the first blade curves from the proximal endportion to the distal end portion, thereby forming an arm.

In some embodiments, the distal end portion of the first blade has aflange extended distally therefrom, wherein the flange is adapted todock into spinal tissue. This flange allows the surgeon to dock theretractor into either an adjacent vertebral body or the target discspace. In some embodiments, the flange is axially adjustable withrespect to the first blade.

In some embodiments in which a retractor has both a NIR-red light windowand an electrode, both the NIR-red light window and electrode arelocated on the same blade of the retractor.

In some embodiments, the NIR/red light window (which is typically thedistal end portion of the red light emitter) has a width, and the windowis located within one such width of the electrode. When the window is soclose to the electrode, there is greater surety that light emanatingfrom the emitter can effectively irradiate the nerve detected by theelectrode. Typically, the window is located within 5 millimeters of theelectrode.

In some embodiments, the retractor is a modified tracheal dilator. FIG.3a discloses a conventional tracheal dilator. This dilator is a usefulstarting point for developing a retractor in a lateral spine systembecause it provides a wide retraction starting from a minimal opening.FIG. 3b discloses an arm 39 of a modified tracheal dilator of thepresent invention, wherein the modified arm has both a red/NIR lightwindow W and an electrode E. The electrode is again formed by simplycoating the entire arm, save the distal end electrode E area, in anonconductive polymer. The light conduit is formed by forming a bore inthe arm that begins at an entry hole H1 in the substantially curvedportion of the arm and exits through an exit hole H2 along a sidewall ofthe distal end portion of the arm. A fiber optic cable (not shown) canthen be fed into the hole and extended until its distal end reaches exithole H2 to form window W. The end surface of the fiber optic cable canbe coated with a reflecting material in order to help the light exitlaterally through the window W of the fiber optic cable. Similarly, theend portion of the fiber optic cable may include in its bulk a quantityof reflective particles in order to help the light exit laterally fromthe fiber optic cable.

In some embodiments, lateral access to the lumbar disc space is providedby first penetrating the transversalis fascia to expose theretroperitoneal fat and visualize the psoas muscle. Next, bluntdissection of the psoas is performed. Next, the surgeon inserts themodified tracheal dilator into the psoas. The modified tracheal dilatoris then expanded to its desired diameter under neuromonitoring. Redlight is irradiated onto a selected nerve adjacent an arm of thedilator, as desired. Next, the desired portion of the annulus fibrosusis removed, and the desired portion of the nucleus pulposus is removed.The endplates are then prepared. The disc space is then distracted by aspreader, and then trialed to select the appropriately sized fusioncage. A lateral fusion cage filled with a bone growth substance is theninserted into the disc space and lightly impacted into place.

In preferred embodiments, the retractor is made out of a conductivemetal so that it can serve as an electrical conduit between theneuromonitoring system and the electrode. In some embodiments, theretractor is made predominantly out of a biocompatible metal such astitanium, cobalt-chrome or stainless steel. However, in others, a firstblade of the retractor comprises a proximal portion made of metal, and adistal end portion made of a plastic, so that the distal portion isdisposable. In one disposable embodiment, the distal end portion isplastic, has a metallic strip coating running along its outer surface tofunction as an electrode, and has a non-metallic reflective surface(such as a white pigment) coating the rest of the component, save oneportion of the outer surface that functions as the light window W.

In some embodiments, the retractor blade has a channel or bore runningsubstantially longitudinally from the proximal end portion to the distalend portion of the blade, and a light delivery catheter is disposed inthe channel or bore. This catheter may be removable, thereby allowing itto be used as a disposable. Preferably, an NIR/red light source isconnected to the proximal end portion of this light delivery catheter,and red/NIR light is emitted from the distal end portion of the lightdelivery catheter through a window W.

In some embodiments having a light delivery catheter, the light deliverycatheter may be connected to an endoscope, thereby providing the surgeonwith an opportunity to visualize nerves adjacent the retractor orcannula.

In some retractor embodiments, a first electrode and a NIR/red lightemitter are each mounted upon a distal end portion of a first blade. Insome embodiments, the NIR/red light emitter is a light emitting diode(LED). Typically, the electrode is in electrical connection with aneuromonitoring system. In some embodiments, a second blade of theretractor has a distal end portion having an NIR/red light emittermounted thereon. Preferably, a second electrode is also present upon thedistal end portion of the second blade.

The red light neuroprotection of the present invention may also be usedin a number of other spinal procedures in which nerve health iscompromised by retractors. For example, in a transforaminal interbodyfusion (TLIF) approach, wherein the exiting root of the dorsal rootganglion may be impacted by a retractor, therapeutic or prophylacticred/NIR light may be irradiated upon the nerve root. In a transforaminalinterbody fusion (TLIF) approach, wherein the traversing root of thedorsal root ganglion may be impacted, therapeutic or prophylacticred/NIR light may be irradiated upon the nerve root. In an anteriorlumbar interbody fusion (ALIF) approach, wherein nerves may be impacted,therapeutic or prophylactic red/NIR light may be irradiated upon thenerve. In an ACDF approach, wherein the recurrent laryngeal andsympathetic nerves may be impacted, therapeutic or prophylactic red/NIRlight may be irradiated upon the nerve. In spinal deformity correction,wherein nerves may be impacted, therapeutic or prophylactic red/NIRlight may be irradiated upon the nerve. In osteotomy retraction andcorrection, wherein nerves may be impacted, therapeutic or prophylacticred/NIR light may be irradiated upon the nerve.

Other clinical uses for the red/NIR light neuroprotection of the presentinvention may be realized in implantable devices for spinal cord injury;implantable “micro diode” devices for radiculopathy (providing longlasting ESI); post operative catheters treating ischemic nerve roots;and LEDs on intramedullary rods and external fixators.

CIP

In some embodiments respecting a lateral approach, the NIR/red light isdelivered from the working channel instrument, such as a retractor. Nowreferring to FIG. 4, preferably, the red light emitter 51 is placed onthe outside surface 53 of at least one blade 55 of the retractor 57.Without wishing to be tied to a theory, it is more advantageous to placethe red light emitter on the retractor (rather than a dilator thatprecedes it). In some embodiments, the red light emitter is placed onthe outside surfaces of a plurality of the blades of the retractor. Insome embodiments, the red light emitter is placed on the outsidesurfaces of each blade of the retractor.

Therefore, in some embodiments, there is provided a surgical retractorcomprising a plurality of blades assembled to form a working channel,wherein at least one blade has an outer surface having a NIR/red lightemitter thereon.

There are many different ways in which the red light may be deliveredthrough the red light emitter. For example, the emitter can be an LED.The emitter can comprise the distal terminus of a fiber optic cablewhose proximal end is connected to a red light source. The emitter canbe a hole in the blade through which red light is shined. The emittercan be a portion of the blade made from an optically transparentmaterial.

In embodiments in which the retractor emits NIR/red light, it ispreferable for light to be emitted from more than just the distal end ofthe retractor. This is because nerves of the lumbar plexus may bepresent in the psoas up to about 5-6 cm from the intervertebral disc.Accordingly, in some embodiments, and now referring to FIG. 5, thedistal-most 20% of the retractor blade emits NIR/red light, in this casethrough an optically clear panel portion 59 of the blade 63. In someembodiments, a red light source (not shown) is placed in the workingchannel of the retractor and shined through optically clear panelportion 59. The remainder portion 61 of the blade 63 may be made of abiocompatible metal. In some embodiments, the distal-most 30% of theretractor blade emits NIR/red light. In some embodiments, thedistal-most 40% of the retractor blade emits NIR/red light. In someembodiments, the distal-most 50% of the retractor blade emits NIR/redlight. Use of these embodiments will help insure that essentially all ofthe potentially distressed nerves of the lumbar plexus can betherapeutically or prophylactically treated with NIR/red light.Similarly, in some embodiments, the distal-most 4 cm the retractor bladeemits NIR/red light. In some embodiments, the distal-most 5 cm theretractor blade emits NIR/red light. In some embodiments, thedistal-most 6 cm the retractor blade emits NIR/red light.

Therefore, in some embodiments, there is provided a surgical retractorcomprising a plurality of blades assembled to form a working channel,wherein at least one blade comprises an optically translucent portion.Preferably, the optically translucent portion is substantially opticallytransparent to red/NIR light. Preferably, the optically translucentportion traverses the thickness of the blade.

Now referring to FIG. 6, in some embodiments in which the retractorblade emits NIR/red light, at least one blade 65 is made of asubstantially optically clear material and NIR/red light is “injected”into the blade from the proximal end portion 67 of the blade. This lightthen travels distally in the blade and is emitted laterally from thedistal end portion of the blade (as shown by arrows). In thisembodiment, the light may be injected into the blade by a fiber opticcable 69 whose distal end is connected to the proximal end portion 67 ofthe blade, whose distal portion runs through the retractor collar 70,and whose proximal end is connected to a NIR/red light source 71.

Preferably, the blade also contains a plurality of light reflectiveparticles 73 that cause the light to be dispersed. Preferably, theseparticles reside in at least the 20-25% distal-most portion of theblade. Thus, when the proximally injected light hits these particles,the light bounces off the particles, exits the blade laterally, andenters a portion of the psoas that contains the nerves of concern.

Therefore, in some embodiments, there is provided a surgical retractorcomprising a plurality of blades assembled to form a working channel,wherein at least one blade comprises a proximal end portion and a distalend portion, and is made of an optically translucent material andcomprises a plurality of reflective particles located in the distal endportion of the blade.

In some embodiments, and now referring to FIG. 7, the reflectiveparticles 73 are present throughout the length of the blade. In somepreferred embodiments thereof, the proximal portion 75 of the outersurface 77 of the blade is coated with a reflective material 79, therebypreventing light from leaving the blade in areas not believed to containnerves of concern. Similarly, the inner surface 81 of the blade maylikewise be coated with the same reflective material.

Still referring to FIG. 7, in some embodiments, the optically clearblade is coated with a light reflective material on the inner surface ofthe blade. In some embodiments, the optically clear blade is coated witha light reflective material on the distal end surface of the blade.These coatings help insure that the light exits the blade only throughthe outer surface of the blade, and so promote the efficient use of theNIR/red light.

Therefore, in some embodiments, there is provided a surgical retractorcomprising a plurality of blades assembled to form a working channel,wherein at least one blade comprises a proximal end portion, a distalend portion, an outer surface and an inner surface, and is made of anoptically translucent material and comprises a plurality of reflectiveparticles located in the distal end portion of the blade, wherein theinner surface and the proximal end portion of the outer surface of theblade has a reflective coating thereon.

In some embodiments, as in FIG. 6, the proximal end portion 67 of theblade is substantially free of reflective particles while the distalportion 68 of the blade comprises light reflective particles. In thisembodiment, light injected through the proximal end of the blade travelsdistally without reflection through the proximal portion of the blade(as shown by the vertical arrow) and then reflects off the particleslocated in the distal portion of the blade and thereby leaves the bladethrough its distal portion (as shown by the horizontal arrow).Preferably, in such embodiments such as FIG. 7, a light reflectivecoating coats the inner surface of the blade. Optionally, in suchembodiments, a light reflective coating coats the proximal end portionof the outer surface of the blade.

Now referring to FIG. 8, in some embodiments in which the proximalportion of the optically clear blade is substantially free of reflectiveparticles while the distal portion of the optically clear bladecomprises light reflective particles, the blade 83 is constructed of twoseparate components—a distal particle-containing component 85 and aproximal particle-free component 87—which are then mechanically joinedto produce an interface 89. These components should be tightly joined tocreate an interface that transmits light effectively.

Therefore, in some embodiments, there is provided a surgical retractorcomprising a plurality of blades assembled to form a working channel,wherein at least one blade comprises:

-   -   a) a proximal end piece made of an optically translucent        material, and    -   b) a distal end piece made of an optically translucent material        and comprising a plurality of reflective particles dispersed        therein,        wherein the proximal end piece and distal end piece are        mechanically joined to create an interface.

In some embodiments in which the proximal portion of the optically clearblade is substantially free of reflective particles while the distalportion of the optically blade comprises light reflective particles, theblade is constructed by first making the distal portion (with theparticles), placing this distal potion in an appropriate mold and thenfilling the mold with a neat liquid of the same optically clear materialused to make the distal end portion. Once the liquid hardens, the resultwill be a unitary blade have the particles only in its distal portion.Optionally, the inner and distal end surfaces of this blade may then becoated with a light-reflective coating.

Now referring to FIG. 9, in some embodiments, the proximal endportion 91of the blade is fitted with at least one receptacle 93 that is adaptedto receive a distal end 95 of a fiber optic cable. By connecting thiscable 69 to a NIR/red light source 71, light can be delivered throughthe cable and into the optically clear blade. Preferably, the proximalend of the blade is fitted with a plurality of such receptacles 93 inorder to receive a plurality of fiber optic cables, and thereby moreevenly spread light across the width of the blade. In some embodiments,the receptacle and the distal end of the fiber optic cable are fittedwith mating locking components that insure near complete transmission ofthe light from the cable to the blade. In some embodiments (not shown),the receptacle(s) is present on the distal end of the blade. In others,however, it is present on the proximal end portion of the outer or innersurface of the blade. In these latter embodiments, the proximal endportion of the optically clear blade (save the receptacle region) iscompletely coated with a light reflective material 97 to ensure thatlight leaves the blade only from the distal end portion 99 of the bladethat preferably comprises light reflecting particles 101.

Therefore, in some embodiments, there is provided a surgical retractorcomprising a plurality of blades assembled to form a working channel,wherein at least one blade comprises a proximal end portion, a distalend portion, an outer surface and an inner surface, and is made of anoptically translucent material and comprises a plurality of reflectiveparticles located in the distal end portion of the blade, wherein theinner surface and the proximal end portion of the outer surface of theblade has a reflective coating thereon, and wherein the proximal endportion of the blade is fitted with at least one receptacle thatreceives a distal end of a fiber optic cable.

Now referring to FIG. 10, there is provided a multi-blade surgicalretractor, comprising:

-   -   a) a first blade 103 made of an optically-clear base material,        the first blade comprising a proximal end portion 105 having a        proximal end surface 107, a distal end portion 109 having a        distal end surface 111, an inner surface 113, and outer surface        115,    -   b) a plurality of reflective particles 73 located substantially        in the distal end portion of the first blade,    -   c) a connector 117 adapted to receive a fiber optic cable 69 and        located on the outer surface of the proximal end portion of the        blade,    -   d) a reflective coating 121 that coats substantially all of the        inner surface of the first blade, and the proximal end portion        of the outer surface of the first blade.

In some embodiments, and now referring to FIG. 11, the retractor blade123 can have a light guide 125 attached to the distal portion of theouter surface of the blade. In some preferred embodiments, the lightguide receives light through a fiber optic cable 69 connected to aNIR/red light source 71 and causes light to be reflected or refractedout of the light guide and toward the lumbar plexus nerves of the psoas.Such a light guide may include a plurality of optical fibers 127 ofdifferent lengths terminating at respective ends 129 at differentlocations over the length and width of the light guide to cause light tobe emitted from the ends 129 of the optical fibers 127 and reflectedtoward the psoas in a pinpoint pattern at different points over thelength and width of the light guide. These fibers may be attached in aparallel fashion to a common (preferably, reflective) backing 131. Insome embodiments thereof, the selected light guide is that disclosed inU.S. Pat. No. 7,686,839 (Parker), the specification of which isincorporated by reference in its entirety. In some embodiments, thebacking of the light guide is attached to the outer surface 133 of themetal retractor blade by an adhesive.

Therefore, in some embodiments, there is provided a surgical retractorcomprising a plurality of blades assembled to form a working channel,wherein at least one blade comprises a distal end portion having anouter surface having a light guide thereon, wherein the light guidecomprises a plurality of optical fibers of different lengths terminatingat respective ends at different locations over the length and width ofthe light guide to cause light to be emitted from the ends of theoptical fibers in a pinpoint pattern at different points over the lengthand width of the light guide.

No referring to FIG. 12, in some embodiments, the light guide (that isattached to the distal end portion of the outer surface of the blade)comprises a plurality of optical fibers 135 having roughened outersurfaces 137. The roughened outer surfaces provide asperities that causethe light travelling longitudinally through the optical fiber to bediverted laterally and thereby exit the optical fiber at many placesalong the length of the optical fiber. Such optical fibers can bearranged in a side-by-side parallel fashion and attached to a common(preferably, reflective) backing.

Therefore, in some embodiments, there is provided a surgical retractorcomprising a plurality of blades assembled to form a working channel,wherein at least one blade comprises a distal end portion having anouter surface having a light guide thereon, wherein the light guidecomprises a plurality of optical fibers having roughened surfaces.

In some embodiments, the light guide (that is attached to the distal endportion of the outer surface of the blade) comprises a single opticalfiber having a roughened outer surface, wherein the single optical fiberis wound in a coil shape. Preferably, the coil has a diameter of about5-6 cm.

In other embodiments, and now referring to FIG. 13, the light guide(that is attached to the distal end portion of the outer surface of theblade) comprises a single optical fiber having a plurality of lightreflective particles 73 contained therein, wherein the single opticalfiber is wound in a coil shape 141. Preferably, the coil has a diameterof about 5-6 cm. Alternatively, the spiral-shaped optical fiber may havea roughened surface as its light dispersive means.

Therefore, in some embodiments, there is provided a surgical retractorcomprising a plurality of blades assembled to form a working channel,wherein at least one blade comprises a distal end portion having anouter surface having a fiber optic cable thereon, wherein the fiberoptic cable comprises a plurality of reflective particles dispersedtherein and is formed substantially in a spiral shape.

Therefore, in some embodiments, there is provided a surgical retractorcomprising a plurality of blades assembled to form a working channel,wherein at least one blade comprises a distal end portion having anouter surface having a fiber optic cable therein, wherein the fiberoptic cable has a roughened surface and is formed substantially in aspiral shape.

In some embodiments, and now referring to FIG. 14, an outside surface143 of the blade has an array of NIR/red LEDs 145 attached thereto.Preferably this array amounts covers a surface area of at least about 20cm², preferably at least about 30 cm². In such embodiments, the array iselectrically connected to a power source 147.

Therefore, in some embodiments, there is provided a surgical retractorcomprising a plurality of blades assembled to form a working channel,wherein at least one blade comprises a distal end portion having anouter surface having an LED array thereon.

A light diffusing panel is a panel of optically clear material that hasreflecting particles dispersed therein. When focused (point source)light is delivered to a backside of the panel, the light becomesdispersed throughout the panel and emerges substantially evenly from thefront side of the panel.

In some embodiments of the present invention, and now referring to FIG.15, a light diffusing panel 151 is attached to the outside surface 153of the blade and light is delivered to a backside of the panel. In thiscase, the light is delivered through an LED 155. The light so deliveredbecomes dispersed throughout the panel and emerges substantially evenlyfrom the front side of the panel.

Therefore, in some embodiments, there is provided a surgical retractorcomprising a plurality of blades assembled to form a working channel,wherein at least one blade is made of an optically transparent materialand comprises a distal end portion having an outer surface having alight diffusing panel attached thereto.

In some light diffusing panel embodiments, the blade may be clear andhave attached thereto at least one point light source directed outward.Light from the point light source is delivered to a backside of thepanel (that is attached to the outside surface of the blade), the lightbecomes dispersed throughout the panel and emerges substantially evenlyfrom the front side of the panel, where it enters the psoas. The pointlight source can be produced by many different avenues. The light sourcecan be an LED attached to the inner surface of the blade. It may be afiber optic cable attached to the inner surface of the blade anddirected outward. The light source may also be a stand-alone device thatis temporarily lowered into the working channel and shined towards theoptically clear blade.

In some light diffusing panel embodiments, the blade may have a lightguide attached thereto, wherein the light guide contains a plurality ofpoint light sources. Upon this light guide, a light diffusing panel maybe placed. This panel converts the light from a series of point sourcesto an evenly distributed pattern of light.

In some light diffusing panel embodiments, and now referring to FIG. 16,the blade 161 may be a biocompatible metal and have a bore 163 beginningat the proximal end surface 165, running distally through the blade andterminating as an opening 167 upon the distal end portion 169 of theouter surface 171 of the blade 173. A fiber optic cable 69 may then beplaced in this bore so that its distal end aligns with the opening uponthe distal end portion of the outer surface of the blade. A lightdiffusing panel 175 may then be placed upon the distal end portion ofthe outer surface of the blade in order to spread the light emanatingfrom the distal end of the fiber optic cable.

Therefore, in some embodiments, there is provided a surgical retractorcomprising a plurality of blades assembled to form a working channel,wherein at least one blade comprises a proximal portion having aproximal end surface, a distal end portion having an outer surface, anda bore running from the distal end surface to the outer surface of thedistal end portion of the blade.

In some embodiments, and now referring to FIG. 17, at least one blade201 of the retractor is made of an optically clear material and light isshined laterally through the distal portion of this blade from ahand-held light source 203 temporarily lowered into the distal portionof the working channel of the retractor. In preferred embodiments, thehand-held light source comprises a proximal handle 205, an intermediateshaft 207 and a distal array 209 comprising a plurality of LEDs 211. Theintensity of the LEDs is such that the surgeon need only keep the arrayin the working channel for less than 10 minutes, preferably between 1and 5 minutes, more preferably between about 1-2 minutes.

Commercial red/NIR light arrays of LEDs having a 30-40 mm width areknown to exist. For example, one red/NIR LED array which is a 30 mm×30mm square is sold by Shenzhen Perry Electronic Company Limited. It isbelieved that such arrays can conveniently fit down the working channelof a standard retractor, which is typically about 36 mm×54 mm when fullyexpanded. In some embodiments, the surgeon can insert the array through54 mm slot and the turn the array 90 degrees as it reaches the lowerparts of the working channel. In some embodiments, this hand-held arrayis placed against a clear posteriormost blade of the retractor. In someembodiments, two arrays measuring about 30 mm×30 mm are attached toproduce a 30 mm×60 mm array. This embodiment has the advantage of beingable to treat in a single episode a region of psoas tissue considered tobe most susceptible. In some embodiments, the outer surface 213 of thearray has a convex shape that conform to the concavity of the innersurface of the blade, so that contact is maintained and light transferefficiency is high.

Therefore, in some embodiments, there is provided a method comprising:

-   -   a) inserting into a patient a surgical retractor comprising a        plurality of blades assembled to form a working channel, wherein        a first blade is made of a substantially optically transparent        material,    -   b) expanding the retractor to form the working channel,    -   c) inserting a red light source into the working channel, and    -   d) activating the NIR/red light source to shine red light        through the first blade and into the patient,    -   e) removing the red light source from the working channel, and        passing a spinal implant through the working channel.

We claim:
 1. A method of protecting nerves, comprising the steps of: a)making an incision in a patient, b) inserting a retractor into thepatient through the incision such that first and second components ofthe retractor are in contact with tissue of the patient, the first andsecond components being movable with respect to one another, c) movingthe first and second components of the retractor relative to one anotherto at least partially create a path to a spine of the patient andretract nervous tissue, d) irradiating tissue adjacent the path with anamount of NIR or red light from an emitter of the first component of theretractor, wherein the emitter comprises a light delivery catheterremovably disposed in a longitudinal channel of the first component, e)detecting the health of the retracted nervous tissue using an electrodeof the second component of the retractor, the electrode being inelectrical connection with a neuromonitoring system, and f) receiving amessage from the neuromonitoring system that provides informationconcerning the health of the retracted nervous tissue.
 2. The method ofclaim 1 wherein the light is NIR light.
 3. The method of claim 1 whereinthe light is red light.
 4. The method of claim 1 wherein the irradiationis carried out in response to a warning.
 5. The method of claim 4wherein the warning is from a neuromonitoring system.
 6. The method ofclaim 1 wherein the irradiation is carried out automatically viadirection from a neuromonitoring system.
 7. The method of claim 6wherein the neuromonitoring system has detected a nerve within apredetermined proximity.
 8. The method of claim 6 wherein theneuromonitoring system has detected a decline in nerve health.
 9. Themethod of claim 1 wherein the irradiation is carried outprophylactically.
 10. The method of claim 1 wherein the path leads to anintervertebral disc space.
 11. The method of claim 1 wherein the path isa lateral path to an intervertebral disc space.
 12. The method of claim1 wherein the path is a posterolateral path to an intervertebral discspace.
 13. The method of claim 1 wherein the path is an anterolateralpath to an intervertebral disc space.
 14. The method of claim 1 whereinthe path is a translaminar path to the intervertebral disc space. 15.The method of claim 1 wherein the light delivery catheter is connectedto a NIR/red light source.
 16. The method of claim 1 wherein theirradiation is carried out for between 30 and 300 seconds.
 17. Themethod of claim 1 wherein the irradiation delivers between about 0.1J/cm² and 30 J/cm² of NIR/red light to the nervous tissue.
 18. Themethod of claim 1 wherein the irradiation is carried out at an intensityof between 10 milliwatts/cm² and 90 milliwatts/cm².
 19. The method ofclaim 1 wherein the nervous tissue is located in a psoas muscle.
 20. Themethod of claim 1 wherein the nervous tissue is in an ischemiccondition.
 21. The method of claim 20 wherein the ischemic condition iscaused by expansion of the retractor.
 22. The method of claim 20 whereinthe ischemic condition is caused by the retractor.
 23. The method ofclaim 1 further comprising the step of: g) passing a spinal implantthrough the path to the spine of the patient.
 24. A method of protectingnerves, comprising the steps of: a) making an incision in a patient, b)inserting a retractor into the patient through the incision such thatfirst and second components of the retractor are in contact with tissueof the patient, the first and second components being movable withrespect to one another, c) moving the first and second components of theretractor relative to one another to at least partially create a path toa spine of the patient and retract nervous tissue, d) irradiating tissueadjacent the path with an amount of NIR or red light from an emitter ofthe first component of the retractor, e) detecting the health of theretracted nervous tissue using an electrode of the second component ofthe retractor, the electrode being in electrical connection with aneuromonitoring system, and f) receiving a message from theneuromonitoring system that provides information concerning the healthof the retracted nervous tissue; wherein the second component is formedfrom a conductive metal partially coated with a non-conductive polymer,a non-coated portion of the conductive metal defining the electrode.